This application claims the priority of German patent document 100 07 120.1, filed Feb. 17, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method for regulating the current flow in a permanently excited synchronous motor for a guided missile having an electromechanical actuating drive for the rudder.
As a result of ever more stringent requirements in respect of dynamics, weight and volume, the use of electromechanical rudder actuating systems in modern guided missiles is increasing. For this purpose, permanently excited synchronous machines with high energy magnets are used as servomotors, due to their low axial mass moment of inertia, their excellent wear resistance and their substantial energy density. For space reasons and because of the low axial mass moment of inertia of the arrangement, force is transmitted to the rudder via a roller spindle driven arrangement, in which the spindle itself is directly linked in a rigid connection to the rotor of the machine. Such a device is described in detail in German patent document DE 196 35 847 C2.
Due to the transmission ratio between the machine and the rudder, the high-frequency spindle drive must be of compact design.
One object of the invention, therefore, is to provide a method of current regulation which results in maximum utilization of the machine at high revolutions.
Another object of the invention is to provide a miniaturized drive that achieves excellent circular acceleration.
To this end, for a given amount of the commanded armature current, the phase position of the impressed machine current must be corrected such that the machine develops maximum torque. In spite of extraneous interference effects, the method must carry out a robust compensation of the phase-frequency characteristic at high rotational speeds. In the case of implementation on a microprocessor, computing time requirements of the method and the requirements concerning scanning time of the control algorithm, are to be kept as low as possible.
These and other advantages are achieved by the method according to the invention, in which the command current is always guided orthogonally to the magnet-wheel flow. Further:
a) from measured current of two voltage phases, a measured magnitude of a current-space pointer is determined and an error value for the current is added to a desired value of the amount via a correction regulator; and
b) from the measured current of two voltage phases as well as from the angle command of the current-space pointer, a measurement for the angle error is determined and added to the desired angle value via a correction regulator.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.